Simple Summary: Thermal ablation (TA) is a non-surgical treatment of cancer that has been used
with success in the treatment of colorectal liver metastases (CLM). TA consists of burning the cancer
and a rim of surrounding tissue (margin) with a special needle placed in the tumor under image
guidance. Despite the technological evolution of TA, tumor progression/recurrence rates remain
higher than expected. We present a method that combines tissue and imaging tests performed
immediately after ablation to determine whether there is complete tumor destruction or remaining
live cancer cells that can cause tumor progression/recurrence. This information can provide guidance
for additional treatments for patients with evidence of residual cancer, i.e.,: additional TA at the same
or subsequent sitting, or additional chemotherapy and short-interval imaging follow-up to detect
recurrence. The presented method proposes a clinical practice paradigm change that can improve
clinical outcomes in a large population of patients with CLM treated by TA.
Abstract: Background: Thermal ablation is a definitive local treatment for selected colorectal liver
metastases (CLM) that can be ablated with adequate margins. A critical limitation has been local
tumor progression (LTP). Methods: This prospective, single-group, phase 2 study enrolled patients
with CLM < 5 cm in maximum diameter, at a tertiary cancer center between November 2009 and
February 2019. Biopsy of the ablation zone center and margin was performed immediately after
ablation. Viable tumor in tissue biopsy and ablation margins < 5 mm were assessed as predictors of
12-month LTP. Results: We enrolled 107 patients with 182 CLMs. Mean tumor size was 2.0 (range,
0.6–4.6) cm. Microwave ablation was used in 51% and radiofrequency ablation in 49% of tumors.
The 12- and 24-month cumulative incidence of LTP was 22% (95% confidence interval [CI]: 17, 29)
and 29% (95% CI: 23, 36), respectively. LTP at 12 months was 7% (95% CI: 3, 14) for the biopsy
tumor-negative ablation zone with margins ≥ 5 mm vs. 63% (95% CI: 35, 85) for the biopsy-positive
ablation zone with margins < 5 mm (p < 0.001). Conclusions: Biopsy-proven complete tumor ablation with margins of at least 5 mm achieves optimal local tumor control for CLM, regardless of the ablation
modality used.

DESCARCATI PDF